The Clean Cat
When coastal oil spills occur, the petroleum will tend to move ashore if there is an incoming tide present. This tidal surge carries contaminate into surrounding estuaries and salt marshes, devastating the local ecosystem. The oil mousse, as it is called, clings to everything in its path, including birds, fishes, mammals and all forms of plant life; the further it is diluted the more surfaces adhesion occurs. The immediate marsh cleanup response starts with containing the affected area with booms to prevent further spread, then either wiping the affected location with absorbent materials, pressure washing, raking/bulldozing, or a combination of all three. Current long-term methods involve either in-situ cutting and burning of the marsh grass, sediment removal and replanting, natural attenuation (biodegradation) or bioremediation.
Bioremediation, by biostimulation or bioaugmentation, has recently emerged as one of the most effective and inexpensive methods of decontaminating groundwater and soils. Of specific importance to this project is biostimulation by the introduction of nitrate amendments to the marsh, which has been shown to increase the rate of hydrocarbon degradation in the sediments by as much as 50%. This technique introduces the need for an apparatus to distribute the stimulant throughout the marsh. Since current methods are costly and inefficient, a system that will not damage the site or disturb the ecosystem would be ideal.
In this project a scale prototype shallow water injection delivery vessel was designed and constructed with a budget of less than $2000. Many ideas were discussed on the most effective means of transporting an injection system in a marsh environment. Many propulsion, flotation and control system ideas were discussed and tested. The use of large paddle wheels with slow spinning motors became the primary objective for the design of the craft, which would provide the vessel with a high amount of torque at a low speed in order to "crawl" through the marsh grass. Flotation was achieved using closed cell polyurethane foam for the needed vessel buoyancy of 500-800 lbs and maximum draft of no more than six inches. The vessel is controlled wirelessly through a single board computer and has the potential of being automated with the addition of a positioning system. This system has been designed as a feasibility model for future implementation of a full-scale prototype and possible production for commercial use.
Available from the National Sea Grant Library (use NHU number to search) or NH Sea Grant
- The clean cat (2002). Stanley Boduch, Matt Manning and Mike Mazzone. Advisors: David Fredriksson, Tom Ballestero and Nancy Kinner.